We are pursuing a new approach for establishing human monoclonal antibody-producing cell lines. The approach is based on the full utilization of the cell-transforming (immortalizing) activity of Epstein-Barr virus (EBV). EBV infection is known to be restricted to a portion of Ig-secreting adult human B lymphocytes. Mostly IgM-secreting lymphoblastoid cells lines can be established, which usually secrete small amounts of antibodies and are unstable. Human myeloma cell lines cannot be obtained by EBV infection because the cells lack EBV receptors. We have demonstrated that the host cell restriction of EBV is determined primarily at the cell membrane level. Transplantation of functional EBV receptors permits infecting any human and animal cell by the virus, including myeloma cells. Implanting EBV receptors onto human B lymphocytes themselves, followed by exposure to EBV, increases the proportion of immortalized IgG-secreting cells by 100 to 300%. We intend, therefore, to use functional EBV receptor-implantation as a tool to direct the remarkable cell-transforming ability of EBV into cells that can be utilized for human monoclonal antibody production. Our efforts will be to establish permanent cultures of human myeloma cells from patients with multiple myeloma. The cells will be isolated by a combination of automatic cell sorting and specific antibody/complement-mediated cytolysis, implanted with EBV receptors, and infected by the virus. The established myeloma cell lines will be used for adapting the rodent hybridoma technique to human systems as follows. First, the cells will be evaluated for the intracellular surface and secretable immunoglobulin production. Then growth characteristics and fusability with human lymphocytes will be determined for each myeloma cell we obtained. Finally, the efficiency and the stability of antibody production by the human hybridoma cells will be determined. In summary, our approach increases the chances of generating stable hybridomas for producing human monoclonal antibodies. Therapeutic applications of the antibodies may then be considered. (2)